diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig | 19 | ||||
| -rw-r--r-- | lib/Makefile | 2 | ||||
| -rw-r--r-- | lib/glob.c | 123 |
3 files changed, 144 insertions, 0 deletions
diff --git a/lib/Kconfig b/lib/Kconfig index a8a775730c09..41bfeec72e40 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -396,6 +396,25 @@ config CPU_RMAP config DQL bool +config GLOB + bool +# This actually supports modular compilation, but the module overhead +# is ridiculous for the amount of code involved. Until an out-of-tree +# driver asks for it, we'll just link it directly it into the kernel +# when required. Since we're ignoring out-of-tree users, there's also +# no need bother prompting for a manual decision: +# prompt "glob_match() function" + help + This option provides a glob_match function for performing + simple text pattern matching. It originated in the ATA code + to blacklist particular drive models, but other device drivers + may need similar functionality. + + All drivers in the Linux kernel tree that require this function + should automatically select this option. Say N unless you + are compiling an out-of tree driver which tells you that it + depends on this. + # # Netlink attribute parsing support is select'ed if needed # diff --git a/lib/Makefile b/lib/Makefile index 8427df95dade..d6b4bc496408 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -137,6 +137,8 @@ obj-$(CONFIG_CORDIC) += cordic.o obj-$(CONFIG_DQL) += dynamic_queue_limits.o +obj-$(CONFIG_GLOB) += glob.o + obj-$(CONFIG_MPILIB) += mpi/ obj-$(CONFIG_SIGNATURE) += digsig.o diff --git a/lib/glob.c b/lib/glob.c new file mode 100644 index 000000000000..0ba3ea86b546 --- /dev/null +++ b/lib/glob.c @@ -0,0 +1,123 @@ +#include <linux/module.h> +#include <linux/glob.h> + +/* + * The only reason this code can be compiled as a module is because the + * ATA code that depends on it can be as well. In practice, they're + * both usually compiled in and the module overhead goes away. + */ +MODULE_DESCRIPTION("glob(7) matching"); +MODULE_LICENSE("Dual MIT/GPL"); + +/** + * glob_match - Shell-style pattern matching, like !fnmatch(pat, str, 0) + * @pat: Shell-style pattern to match, e.g. "*.[ch]". + * @str: String to match. The pattern must match the entire string. + * + * Perform shell-style glob matching, returning true (1) if the match + * succeeds, or false (0) if it fails. Equivalent to !fnmatch(@pat, @str, 0). + * + * Pattern metacharacters are ?, *, [ and \. + * (And, inside character classes, !, - and ].) + * + * This is small and simple implementation intended for device blacklists + * where a string is matched against a number of patterns. Thus, it + * does not preprocess the patterns. It is non-recursive, and run-time + * is at most quadratic: strlen(@str)*strlen(@pat). + * + * An example of the worst case is glob_match("*aaaaa", "aaaaaaaaaa"); + * it takes 6 passes over the pattern before matching the string. + * + * Like !fnmatch(@pat, @str, 0) and unlike the shell, this does NOT + * treat / or leading . specially; it isn't actually used for pathnames. + * + * Note that according to glob(7) (and unlike bash), character classes + * are complemented by a leading !; this does not support the regex-style + * [^a-z] syntax. + * + * An opening bracket without a matching close is matched literally. + */ +bool __pure glob_match(char const *pat, char const *str) +{ + /* + * Backtrack to previous * on mismatch and retry starting one + * character later in the string. Because * matches all characters + * (no exception for /), it can be easily proved that there's + * never a need to backtrack multiple levels. + */ + char const *back_pat = NULL, *back_str = back_str; + + /* + * Loop over each token (character or class) in pat, matching + * it against the remaining unmatched tail of str. Return false + * on mismatch, or true after matching the trailing nul bytes. + */ + for (;;) { + unsigned char c = *str++; + unsigned char d = *pat++; + + switch (d) { + case '?': /* Wildcard: anything but nul */ + if (c == '\0') + return false; + break; + case '*': /* Any-length wildcard */ + if (*pat == '\0') /* Optimize trailing * case */ + return true; + back_pat = pat; + back_str = --str; /* Allow zero-length match */ + break; + case '[': { /* Character class */ + bool match = false, inverted = (*pat == '!'); + char const *class = pat + inverted; + unsigned char a = *class++; + + /* + * Iterate over each span in the character class. + * A span is either a single character a, or a + * range a-b. The first span may begin with ']'. + */ + do { + unsigned char b = a; + + if (a == '\0') /* Malformed */ + goto literal; + + if (class[0] == '-' && class[1] != ']') { + b = class[1]; + + if (b == '\0') + goto literal; + + class += 2; + /* Any special action if a > b? */ + } + match |= (a <= c && c <= b); + } while ((a = *class++) != ']'); + + if (match == inverted) + goto backtrack; + pat = class; + } + break; + case '\\': + d = *pat++; + /*FALLTHROUGH*/ + default: /* Literal character */ +literal: + if (c == d) { + if (d == '\0') + return true; + break; + } +backtrack: + if (c == '\0' || !back_pat) + return false; /* No point continuing */ + /* Try again from last *, one character later in str. */ + pat = back_pat; + str = ++back_str; + break; + } + } +} +EXPORT_SYMBOL(glob_match); |